Solar energy and the greenhouse effect- The main shaping force ofour climate is solar energy in the form of sunlight. It strikes Earth’s surface, and some is reflected back into space while some is absorbed and converted into heat. Some of that heat goes into space and some is trapped in the biosphere. biosphere. The balance between heat that stays in the biosphere and heat lost to space determines Earth’s average temperature. The balance is controlled by the greenhouse gases (carbon dioxide, methane, and water vapor). These gases function like glass in greenhouses. They let in light, but they trap heat. A higher concentration of greenhouse gases leads to more heat trapped in the atmosphere which leads to higher temperatures. This phenomenon is known as the greenhouse effect. The greenhouse gases pass in and out of
Unit 2: Ecologythe atmosphere as part of nutrient cycles.
Unit 2: EcologyLatitude and Solar energy- Solar energy ismost intense near the equator as the sun isalmost directly overhead at noon all year.This is why equatorial regions are generallyso warm. The solar energy that most directlyhits regions near the equator has to spreadacross the whole globe. The fact that theEarth is curved makes it harder for the solarenergy to reach the north and south poleswhich is why the climate of the regions awayfrom the equator are cooler than the regions near the equator. There are three different tropical zones created by this distributionof solar energy: tropical, temperate, and polar. The tropical zone, or tropics, which includes the equator, is located between 23.5° north and 23.5° south latitudes. This zone receives nearly direct sunlightall year. On either side of the tropical zone are the two temperate zones, between 23.5° and 66.5° north and south latitudes. Beyond the temperate zones are the polar zones, between 66.5° and 90° north and south latitudes. Temperate and polar zones receive very different amounts of solar energyat different times of the year because Earth’s axis is tilted. As Earth revolves around the sun, solar radiation strikes different regions atanglesthat vary from summer to winter. During winterin the temperate and polar zones, the sun is much lower in the sky, days are shorter, and solar energy is less intense.Heat Transport in the Biosphere- The unequal distribution of heat across the globe creates wind and ocean currents, which transportheat and moisture.Earth has winds because warm air is less denseand rises, and cool air is denser and sinks. For this reason, air that is heated by a warm area of Earth’s surface—such as air near the
Unit 2: Ecologyequator, for example—rises. As this warm air rises, it expands and spreads north and south, losing heat along the way. As it cools, the air sinks. At the same time, in cooler regions, near the poles, chilled air sinks toward Earth’s surface, pushing air at the surface outward. This air warms as it travels over the surface. And as the air warms, it rises. These upward and downward movements of aircreate winds. Winds transport heat from regions of rising warmer air to regions of sinking cooler air. Earth’s rotation causes winds to